The subroutine GUSTEP

The current track parameters are available in the common /GCTRAK/ together with all variables necessary to the tracking routines for the control of the step size. In addition, a few flags and variables are stored in the common block /GCTRAK/ to record the history of the current step:

• The flag INWVOL informs on the boundary crossing:

  0

  transport inside a volume;

  1

  entering a new volume or beginning of new track;

  2

  exiting a volume;

  3

  exiting the first mother;

• The flag ISTOP informs on the particle status:

  0

  normal transport;

  1

  particle has disappeared (decay, interaction...);

  2

  particle has crossed a threshold (time, energy...).

• The array LMEC informs on the mechanisms active in the current step. The mechanism names are stored in ASCII equivalent in LMEC(1...NMEC).
• The total energy loss in the current step is stored in the variable DESTEP.

This information is necessary for the user to take the proper actions in the subroutine GUSTEP which is called by GTRACK at the end of every step and when entering a new volume.

The variable NGKINE in common /GCKING/ contains the number of secondary particles generated at every step, and which are stored in the same common. Depending on the application and on the particle type the user may then take the appropriate action in GUSTEP:

• ignore the particle;
• store the secondary produced in the JSTAK stack for further tracking;
• store the secondary also in the JKINE/JVERTX structure where it will be kept till the end of the event.